Development of novel active polypropylene based packaging films containing different concentrations of sorbic acid

Active polypropylene (PP) based packaging films containing sorbic acid (SA) at concentrations of 2, 4 and 6% w/w were prepared using extrusion molding method. Mechanical, physical, spectroscopy and microbial properties of the films were evaluated. The results showed a significant (P < 0.05) improvement in tensile strength and depressing in elongation at break. Incorporating higher contents of SA diminished water vapor permeability and the transparency of the films. Nevertheless, PP-SA films showed UV absorption which increased significantly (P < 0.05) by increasing SA concentration to 4 and 6% (w/w). Color attributes (L*, a* and ΔE) of PP-SA films were not significantly (P > 0.05) different from those of control film. Increasing SA concentration to more than 2%, led to an increase in b* and yellowness index, while decreased whiteness index. PP-SA films showed antibacterial properties against E. coli and S. aureus as well as antifungal effects on A. niger. Antifungal effects of active films were more noticeable than their antibacterial effects.